Thousands of British Airways passengers are still facing long lines, confusion and canceled flights as the airline works to restore its computer systems after a global IT failure crippled its services.

The airline said that it hoped to operate a “near normal schedule” at Gatwick and the “majority of services” from Heathrow on Sunday, a day after canceling all flights from both London airports.

“Work continues to restore all of our IT systems but we expect some further disruption today,” BA said in a statement.

BA canceled flights from Heathrow and Gatwick Saturday, upending the travel plans of tens of thousands of people on a busy U.K. holiday weekend. It blamed a power supply issue for the outage and said there was no sign it was under cyberattack.

BA operates hundreds of flights from Heathrow and Gatwick on a typical day — and both are major hubs for worldwide travel.

Passengers — some of whom had spent the night at the airport — faced long lines to check in, re-book or find lost luggage on Sunday. Dozens more flights from Heathrow were canceled.

“Everyone is upset. There’s people in tears,” said Melanie Ware, who flew in from Los Angeles and was trying to get to Venice on her honeymoon.

“We rebooked for Venice for tonight, which they also have canceled now,” she told Sky News. “So we have no way of getting out of Heathrow and they haven’t compensated us for anything, and we’re stuck and this is the worst honeymoon ever.

“British Airways has ruined our honeymoon.”

Tonda Sallee, who was trying to fly to Frankfurt, said she been in line for five hours, “and we have no idea how long we’ll be in line. The rest of the day I’m sure, and we probably won’t fly out today either.”

Many passengers complained about a lack of information from the airline.

“Some 80-year-old lady was standing around waiting for announcements, et cetera, and she fell over,” said Londoner Terry Page, who managed to get on one of the last flights from Heathrow to Dallas-Fort Worth on Saturday. He and other passengers arrived, but their luggage did not.

“We helped her up and she said ‘I’m just so tired,'” Page said. “It’s been a terrible, terrible day.”

While not that frequent, when airline outages do happen, the effects are widespread, high-profile and can hit travelers across the globe.

BA passengers were hit with severe delays in July and September 2016 because of problems with the airline’s online check-in systems.

In August 2016, Delta planes around the world were grounded when an electrical component failed and led to a shutdown of the transformer that provides power to the airline’s data center. Delta said it lost $100 million in revenue as a result of the outage.

(AP)